SAM-5 definition of physical reconfiguration

Ballard, Curtis C (HP Storage) curtis.ballard at
Tue Jan 6 14:54:04 PST 2015

Formatted message: <a href="">HTML-formatted message</a>

I’m not certain that just removing ‘physical’ solves the problem but I
do agree that reconfiguration of virtual SCSI target devices can and should
be able to cause this.	We have devices that are able to be software
reconfigured so that virtual ports are enabled/disabled and we consider that
to ‘virtually’ be a physical reconfiguration.

The last time I looked at this we concluded that it took something
significant like a port add/delete to justify changing a relative port
identifier and that an external change like a cable pull/plug or a SCSI
change like an ADI port enable/disable command shouldn’t cause a change.

Curtis Ballard

Hewlett Packard

From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Ericson,

Sent: Tuesday, January 6, 2015 3:37 PM

To: Gerry Houlder; T10 Reflector

Subject: RE: SAM-5 definition of physical reconfiguration

The simple fix is to remove the word “physical” from the referenced
sentence.   Reconfiguration of “virtual” SCSI target devices has been the
practice for a very long time.	I expect an INQUIRY DATA HAS CHANGED event.


From: owner-t10 at<mailto:owner-t10 at> [mailto:owner-t10 at]
On Behalf Of Gerry Houlder

Sent: Tuesday, January 06, 2015 4:52 PM

To: T10 Reflector

Subject: Re: SAM-5 definition of physical reconfiguration

i tend to think of physical reconfiguration as a hardware change thing.
Changing cables around, moving a card from one slot to another, flicking a
switch. Things that are outside the scope of SCSI standards. i would consider
things that can be done with SCSI commands (e.g., MODE SELECT) to be more of
a logical reconfiguration that should't change a port identifier.

I will concede that we are now defining SCSI commands that can create or
remove logical units. This allows commands to create a virtual logical unit
in one location, tear it down, and recreate the same numbered logical unit in
another location within the same domain and have the same result as swapping
some cables or moving a PC card from one backpanel slot to another. This
muddies things a bit.

On Tue, Jan 6, 2015 at 3:10 PM, Kevin D Butt
<kdbutt at> wrote:

In of SAM-5r18 there is the following sentence.

The relative port identifier for a SCSI port shall not change once assigned
unless physical reconfiguration of the SCSI target device occurs.

What is the definition of "physical reconfiguration"?

Within my company I have opinions that oppose each other.

 1) physically change cables that are connected

 2) change the configuration settings (e.g., mode select)


Kevin D. Butt

SCSI Architect, Tape Firmware, T10 Standards

Data Protection & Retention

MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744

Tel: 520-799-5280<tel:520-799-5280>

Fax: 520-799-2723<tel:520-799-2723> (T/L:321)

Email address: kdbutt at

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